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OT power supply question

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wt5y@netzero.net

OT power supply question

I use a Pyramid power supply. PS35G to be exact. Sometimes when I turn it on it makes a thudding sound. But it works fine and it doesnt do it all the time. I am not the original owner and Ive had it for a couple years so I know its getting pretty old by now. Wondering what would make that noise. Kinda sounds like someone hit a metal box with a mallet best I can describe it.

WT5Y
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Mike WA8BXN

Re: OT power supply question

Probably inrush current charging the capacitor(s), I have heard it in other
supplies (astron). You could shock mount the transformer maybe if it bothers
you too much!
73/72 - Mike WA8BXN

-------Original Message-------

I use a Pyramid power supply. PS35G to be exact. Sometimes when I turn it on
it makes a thudding sound.
WT5Y
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Tom Hammond-3

Re: OT power supply question

In reply to this post by wt5y@netzero.net

That 'thudding' is the transformer going "Ugh" during the first half-cycle
(or full-cycle) of AC which it's trying to charge the completely DIScharged
electrolytic in the supply.

My Astrons all do that was well.

73,

Tom N0SS

At 11:31 AM 12/16/04, you wrote:

>I use a Pyramid power supply. PS35G to be exact. Sometimes when I turn
>it on it makes a thudding sound. But it works fine and it doesnt do it
>all the time. I am not the original owner and Ive had it for a couple
>years so I know its getting pretty old by now. Wondering what would make
>that noise. Kinda sounds like someone hit a metal box with a mallet best
>I can describe it.
>
>WT5Y
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

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Tom Mc

Re: OT power supply question

In reply to this post by wt5y@netzero.net

My Astron does it also, I suspected it was the capacitors, now thanks to you guys I know for sure.

Now, can someone tell me why I make the same noise when my wife wakes me up at 5 am to get me off to work???

Happy Holidays to all,

Tom
WB2QDG
K2 1103

----- Original Message -----
From: "[hidden email]" <[hidden email]>
Date: Thursday, December 16, 2004 12:31 pm
Subject: [Elecraft] OT power supply question

>
> I use a Pyramid power supply. PS35G to be exact. Sometimes when
> I turn it on it makes a thudding sound. But it works fine and it
> doesnt do it all the time. I am not the original owner and Ive
> had it for a couple years so I know its getting pretty old by now.
> Wondering what would make that noise. Kinda sounds like someone
> hit a metal box with a mallet best I can describe it.
>
> WT5Y
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>